Use of elastic waves to study relaxation in metallic glasses

Abstract Metallic glasses may be formed in a large number of metal alloys by quenching the appropriate liquid at rates of the order of 106 K s−1. This is usually achieved by melt spinning which produces thin ribbons or tapes of the material. In their as-quenched state, metallic glasses are highly metastable with respect to not only the crystalline state, but also a denser glassy structure of lower energy. Consequently, on subsequent annealing these glasses undergo a number of subtle structural changes usually described as ‘structural relaxations’. We have used a sensitive pulse-echo technique to monitor the changes in Young's modulus during these relaxations. The total change in modulus is high (∼ 10%) and the change during isothermal annealing can be fitted to an expression of the type ∆ E = k T α (